1. Technical Field
The following description relates to one or more image forming devices.
2. Related Art
FIG. 5 is a side view schematically showing an entire configuration of a known image forming device with a manual sheet feed device incorporated therein. In the image forming device, a right side in FIG. 5 corresponds to a front face (operation face), on which handles 51 of sheet feed cassettes 12 and 12a and a manual sheet feed slot 40 are provided.
A sheet 14 of a normal size fed from the sheet feed cassette 12 or 12a by a sheet feed roller 13 is carried by a carrying roller 11, through timing adjustment by a pair of registration rollers 15, toward a transfer portion under a belt photoconductive body 16. A toner image is formed on the photoconductive body with an electrification charger 17, a laser scanning optical system, and a developing unit that are provided around the photoconductive body 16 in an order of a turning direction indicated by an arrow. The toner image formed is transferred onto the sheet 14 due to operation of a transfer charger 20. The toner image transferred on the sheet 14 is fixed by a fixing unit 21. Then, the sheet 14 with the toner image fixed thereon is discharged with a pair of sheet discharge rollers 23 and a switching claw 24 of a sheet discharge unit 22, via sheet discharge guides 25 and 26 and a pair of sheet discharge rollers 27 and 28, from a sheet discharge slot 29 to a stack portion 30 provided on an upper unit with an image-formed surface down, or from a rear sheet discharge slot 31 to a catch tray T with the image-formed surface up.
Further, a sheet loading tray 32 is provided in the vicinity of the manual sheet feed slot 40, and a sheet placed in the sheet loading tray 32 is carried with the carrying roller 11 (for example, see Japanese Patent Provisional Publication No. HE15-238607). In general, rollers provided in a sheet carrying route are adopted such that a roller provided on a further downstream side in a carrying direction carries a sheet at a lower carrying speed. For example, in the aforementioned known image forming device, when a sheet is conveyed from the sheet feed cassette 12 or 12a, each roller is adopted such that a circumferential velocity thereof is higher in an order of the sheet feed roller 13, the carrying roller 11, and the pair of registration rollers 15.
This is because a production tolerance is required for manufacturing of each sort of rollers since it is hard to form each sort of rollers in the same shape.
For instance, even though the sheet feed roller 13, the carrying roller 11, and the pair of registration rollers 15 are all designed to rotate at an identical circumferential velocity, the carrying speed for the sheet is not constant due to the production tolerance of each roller. Therefore, a sheet might be carried in a strained state. When a sheet is conveyed in a strained state, a member employed in the carrying route might be damaged and shifted from an appropriate position thereof. To avoid such undesired situations, in general, each roller is adopted such that a roller provided on a further downstream side in the carrying direction carries a sheet at a lower carrying speed. Thereby, a sheet is conveyed in a manner bent between any couple of adjacent rollers in the carrying direction.